Pointer metadata: add tracking issue number

[rust.git] / library / core / src / ptr / mut_ptr.rs

diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index 785bf70c2992c4395fd2242933ee4c18d81beac4..6651c3dd4e86bd90dd2657870f548f4c918411fb 100644 (file)
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -47,6 +47,17 @@ pub const fn cast<U>(self) -> *mut U {
         self as _
     }
 
+    /// Decompose a (possibly wide) pointer into is address and metadata components.
+    ///
+    /// The pointer can be later reconstructed with [`from_raw_parts_mut`].
+    #[cfg(not(bootstrap))]
+    #[unstable(feature = "ptr_metadata", issue = "81513")]
+    #[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
+    #[inline]
+    pub const fn to_raw_parts(self) -> (*mut (), <T as super::Pointee>::Metadata) {
+        (self.cast(), super::metadata(self))
+    }
+
     /// Returns `None` if the pointer is null, or else returns a shared reference to
     /// the value wrapped in `Some`. If the value may be uninitialized, [`as_uninit_ref`]
     /// must be used instead.
@@ -740,7 +751,7 @@ pub const fn wrapping_add(self, count: usize) -> Self
     }
 
     /// Calculates the offset from a pointer using wrapping arithmetic.
-    /// (convenience for `.wrapping_offset((count as isize).wrapping_sub())`)
+    /// (convenience for `.wrapping_offset((count as isize).wrapping_neg())`)
     ///
     /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
     /// offset of `3 * size_of::<T>()` bytes.
@@ -1162,9 +1173,14 @@ impl<T> *mut [T] {
     #[unstable(feature = "slice_ptr_len", issue = "71146")]
     #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
     pub const fn len(self) -> usize {
-        // SAFETY: this is safe because `*const [T]` and `FatPtr<T>` have the same layout.
-        // Only `std` can make this guarantee.
-        unsafe { Repr { rust_mut: self }.raw }.len
+        #[cfg(bootstrap)]
+        {
+            // SAFETY: this is safe because `*const [T]` and `FatPtr<T>` have the same layout.
+            // Only `std` can make this guarantee.
+            unsafe { Repr { rust_mut: self }.raw }.len
+        }
+        #[cfg(not(bootstrap))]
+        metadata(self)
     }
 
     /// Returns a raw pointer to the slice's buffer.